Recovering occluded tin



Patented Mar. 18, 1924.

HARRY H. ALEXANDER, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO AMERICANSMELTING- AND REFINING COMPANY,

NEW JERSEY.

No Drawing.

To all whom it may concern:

Be it known that I, HARRY H. ALEXAN- DER, a citizen of the UnitedStates, and resident of Westfield, in the county of Union and State ofNew Jersey, have invented certain new and useful Improvements inRecovering Occluded Tin, of which the following 1s a specification.

The invention relates in general to a pr0cess for recovering an alloy oftin and iron, and also occluded tin from the molten slag resulting fromthe smelting of stanniferous ore containing iron or ferrous compounds.

Among the objects of the invention are to obtain occluded metallic tinfrom molten tin bearing slag, to reduw any stannous oxide which may bepresent in the slag, and simultaneously to form an alloy of tin and11011. I

More or less tin is always carried over by the slag resulting from thesmelting of im pure tin ores in a blast furnace. This percentage may beas low as two per cent to five per cent if the ore is smelted under suitable conditions according to the methods set forth in my copendingapplications, Serial Nos. 419,473, 419,474 and 419,475.

If the ore is smelted by other methods, such as are now in common use,however, the percentage of tin in the slag is much higher, andfrequently the slag contains as much as ten per cent to fifteen per centof the total tin content of the ore.

The resent invention features the step of stirrlng into the molten slaga suitable reducing agent, such as carbonaceous material, usually in theform of fine coal, and also a suitable flux, such as limestone, andthese agents are added in quantity and under conditions which will causeany stannous oxide present to be reduced, and an alloy of tin and ironto be formed, which may be separated subsequently from the slag.

The slag while still molten from the blast furnace and withoutappreciably coolin is delivered to a settling furnace of stan andconstruction and provided with a stirrer or other appropriate means foragitating the slag. The reducing and fluxing agents are stirred into themass by the agitator or other means so as to become thoroughly dissem1-nated through the mass and be brought into contact with the tin or tincompounds which may be present. The occluded metallic tin OF NEW YORK,N. Y., A CORPORATION OF BEOOVERING OCCLUDED TIN.

Application filed October 25, 1920. Serial No. 419,476.

slowly settles out. Any stannous oxide that is present and thenon-ferrous compounds of tin, such as silicates of tin, are reduced.During the operation a portion of the tin will combine with iron whichis present in the slag under the conditions existing to form an iron tinalloy. The stirring of the charge may be continued "for a varying periodof five to ten hours depending upon the mass 'of the charge and theextent'to which it is desired to clean the slag. Slags containing lessthan one per cent of tin can be obtained by regulating the period ofstirring and the quantity of reducing material and fluxes that areadded.

It is possible by this method not only to recover some of the occludedtin in the form of metallic tin, but also to recover practically all ofthe remaining tin in the form of an alloy With iron, which may betreated by the method disclosed in my co-pending application Serial No.419,475. It will made by those skilled in the art without dey partingfrom the spirit of the invention.

1Having thus described my invention, 1 c a1m:-

l. The process of recovering metallic tin from the slag produced in theblast furnace smelting of stanniferous ores containing iron, whichconsists in supplying the molten slag to a settling furnace, stirringthe mass, adding a reducing agent thereto while maintaining the same ina molten condition whereby to reduce the tin and promote the formationof an iron tin alloy, and then separating said alloy from the slag.

2. The process of recovering metallic tin from the slag produced in theblast furnace smelting of stanniferous ores containing iron, whichconsists in supplying the molten slag without appreciably cooling thesameto a settling furnace, slowly stirring the n 7 menace ma'ss, addingareducing agent and a flux tling furnace, and permitting the occludedthereto while maintaining the same in a tin to settle out whlle stirringinto the hot molten condition thereby to reduce the tin material areducing agent to form an alloy and promote the formation of. an irontin of tin and iron and separating the alloy 6 alloy, and thenseparating said alloy from from the resultin slag. 15

the slag. 1 Signed at New %(ork city in the county of 3.- In the art ofextracting tin from ma- New York and State of New York this 13th terialswhich contain tin-and iron, the procday of Oct. A. D. 1920. ess whichconsists in pouring the material 10 while in a molten condition into aslag set- HEY H. ALENDER.

